Leather water repellent



. droxylated aliphatic solutions.

Reissues Sept- 28, 1954 Chester Carlyle Currie,

to Dow Corning Corporation, corporation of Michigan No Drawing. orls n in 16, 1954, Serial No. 3

Midland, Miclm, a 1

0. 2,672,455, dated March 02,620, August 4, 1952.

' Application for reissue June 2 4, 1954, Serial No.

10 Claims.

reissue specification: matter printed in italics 7 (Cl. 260-291) H Matter enclosed in heavy brackets II II appears in the original patent but forms no part of this This invention relates to a water repellent composition and leather impregnated therewith.

The water repellent composition comprises a mixture of (-1) 15 to 50 per cent by weight of the fora lrvdrolyzable titanium compound of mula Ti(OR )4 or an aliphatic hydrocarbon soluble partial hydrolyzate thereof, in which titanium compounds R-is an aliphatic hydrocarbon radical of less than 13 carbon atoms or a hyhydrocarbon radical of less than 13 carbon atoms containing less than 4 hydroxyl groups; (2) 5 to 70 per cent by weight of a methylpolysiloxane resin composed oi trimethylsiloxane units and Si02 units in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to 25:1; and (3) 15 to 80 per cent by weight of polysiloxanes having the general formula where B may bean alkyl or [alkylene] alloenyl.

indicates the additions made by reissue.

. 2 j compositions of this invention is preferred with best results being obtained with leather containing to 20 per cent of these water repellent radical of less than 4 carbon atoms, or a monocyclicaryl radical and where "n has an average value of 2.0 to 2.9 inclusive.

The compositions of this invention may be applied to any type of leather. tanned, tawed or otherwise cured, and to finished or unfinished leather.

Asa result of impregnation with the compositions of this invention leather is obtained having a resistance to from five fold to one hundred fifty fold increase over those previously known.

Application of the compositions to leather may be readily accomplished by brushing or dipping and may be applied to leather sheets or leather articles such as shoes, belts, etc. These repellent compositions may be employed in the form of solvent-less pastes which may, if desired, contain polishing agents, or in the form of solvent Preferably (at least on a commercial scale) application is accomplished by employing a solvent solution using any solvents which are harmless to leather e. 'g. non-aromatic solvents such as Stoddard etc. Excellent results are obtained by impregnating leather to the extent of 1 to 30 per cent by weight of the water repellent composition (based on the weight of the leather). The impregnation of greater amounts is ordinarily not necessary although excellent water repellency' may be obtained by impregnating up to 50 per cent. Leather containing 2 to per cent by weight of the Solvent, naphtha mineral spirits.

water penetration ranging with an acidic silica sol.

compositions. As many applications of these compositions to leather as is necessary to eilfect the desired degree of impregnation may be employed. Ordinarily two applications with a 15 per cent solution is sufficient.

The methylpolysiloxane resinous copolymer composed of trimethylsiloxane units and S102 units employed herein, may be prepared by the cohydrolysis of (CI-LhSiX and SiX4 where X is a hydrolyzable radical, employing, of course, such proportions as necessary to obtain the desired CHs/Si ratio of from 1.021 to 2.5:1. Preferred are resinous copolymers having a methyl to silicon ratio of from 1.011 to [2.5:l.] 1.5:1. Alternatively this copolymer may be prepared by reacting (CI-IahSiCl, (CH3)3S1OC2H5 or (crnnsiosucrma Such a method is fully described in the copending application of William H. Daudt and Leslie J. Tyler, Serial No. 184,720, filed September 13, 1950, and assigned to the same assignee as this invention. The copolymers of trimethylsiloxane and SiOz referred to supra are characterized by being readily soluble or dispersable in organic solvents.

The titanium compounds suitable for employment in the composition of this invention are those esters having the general formula Ti(OR.)4 where R is an aliphatic hydrocarbon radical of less than 13 carbon atoms, or a hydroxylated aliphatic hydrocarbon radical of less than 13 car' bon atoms and containing less than 4 OH radicals, and partially hydrolyzed Ti(0R)4 compounds that are substantially soluble in aliphatic hydrocarbon solvents. Thus titanium esters such as tetramethyl titanate, tetraethyl titanate, tetradecyl titanate, octylene glycolyl titanate, tetra 2- ethyl hexyl titanate, tetradodecyl titanate, tetraisopropyl titanate, and any mixtures thereof may be used. Titanium esters wherein R is the same or mixed radicals are likewise suitable. Preferably, the R groups should have at least 3 carbon atoms. These esters are prepared ordinarily by ester interchange of a titanium ester such as tetramethyl titanate with a higher boiling alcohol. For example, octylene glycolyl titanate is readily prepared by reacting octylene glycol with tetramethyl titanate in molar proportion of 4 to 1. Partially hydrolyzed Ti(OR)4 compounds may be employed if the hydrolysis has not rendered (such as Stoddard solvent). Ii partially hydrolyzed titanium compounds are employed particular care is necessary to prevent undue formation of insoluble TiOz. n the basis oi commercial availability, tetrabutyl titanate is preferred. All of the titanium esters mentioned in the examples of this application are commerically available.

The third essential ingredient employed herein is organopolysiloxanes having the general formula where B may be alkyl or [alkylene] alkenyl radicals of less than 4 carbon atoms, or monocyclicaryl radicals, and n has ary average value 01' 2.0 to 2.9 inclusive. These materials are employed in amount of from 15 to 85 per cent by weight of the total composition. Specific examples of operative siloxanes are dimethylpolysiloxane, vinylmethylsiloxane, phenylethylsiloxane, dipropylsiloxane, methylxenylsiloxanes or any mixtures thereof. Also copolymers of 'such diorganiosiloxanes with triorganosiloxanes such as trimethylsiloxane, phenyldimethylsiloxane, etc. are operative. Traces of monoorganosiloxane units may also be present in these siloxanes as long as the value 01 remains substantially in the range specified.

These organosiloxanes are benzene soluble materials which vary in viscosity from thin fluids to deformable solids. Generally preferred are fluid polymers having viscosities ranging from to 100,000 centistokes at 25 C. Methylpolysiloxanes are the preferred species.

The above components may be mixed in the solvent free state by employing common mixing equipment. It is generally more convenient, however, to eflect mixing by employing solvents which may be retained after mixing to yield solutions Suitable leather polishing waxes and dyes may be added to the compositions of this invention. Any solvent may be employed which is harmless to leather and capable of dispersing the compositions of this invention.

The outstanding advantages of this invention ready for use.

are clearly demonstrated by impregnating leather and testing in the manner described below.

The leather impregnated in the examples is Tomahawk Kip, a commercial emulsion top vegetable tanned cowhide. However, the products of this invention are equally applicable to leather from horse hide, pig skin, and other animals.

Sample pieces of such leather measuring 4 x 4% inches and varying between 0.05 and 0.06 inch in thickness were tested in an Upper Leather Water Penetration Machine. This machine is a slight modification of the machine pictured and described on pages 401-2 of the August 1947, issue of "Journal of the American Leather Chemists Association. This testing machine consists of a pair of v clamping heads, one oi such heads being movable downward over an arc of 30. The leather sample is clamped to the V heads to form thereby a leather trough which is sealed at each end by means of gasketed V blocks.

The leather trough so formed is partially immersed in water and flexed by the movable head. Such flexing produces a single wrinkle in the center of the trough and simultaneously places the upper edges or the leather trough under tension. The machine runs at 72 flexes per minute. The number of cycles required for leather to wet through is determined by observing the appearance of a tiny bead 01' water which usually appears at either end 01' the wrinkle. The number of cycles required for the appearance of this drop of water is known as the "first drop munber.

This invention is illustrated by the following examples but is not limited except as defined in the claims. not obtained employing mixtures whose ingredients are in proportions outside the scope set forth in the claims.

EXAMPLE 1 Samples 01 leather were impregnated by dipping in Stoddard Solvent (B. P. 308-380" F.) solutions containing the compositions of Table 1. Samples were immersed for 30 seconds and then air dried for 16 hours, then reimmersed for 30 seconds and again air dried for 16 hours prior to testing. The amount 01 impregnation (expressed as per cent pickup) based on the weight of the leather was determined by diflerence in weight. All impregnated samples were tested in the Upper Leather Penetration Machine and the "first drop" numbers arerecorded in Table I.

Mixtures tabulated in Table I were made by mixing the following materials A, B, and C in various proportions.

A. A methylpolysiloxane copolymer composed of (CI-1203810 units and S10: units having a CHsSl ratio of 1.21.

B. A methylpolysiloxane having the composition 97 mol per cent (CI-192810 and 3 mol per cent (CI-IahSiOg.

C. Tetrabutyl titanate.

Mixing was readily accomplished by dissolving all components in Stoddard Solvent (B. P. 308- 380 F.) and adjusting the total solids to 15 per cent by weight. Check samples were tested in all cases and the average first drop" values tabulated in Table I.

TABLE I Composition 0! Mixture in percent by Average Average Wei ht percent No. of Mixture No. 3 pickup flexes by first (B) (0) weight drop 13. 8 176 19. 6 101 100 5. 2 167 17. 5 i4. 1 l, 633 16. 67 18. 2 4!, 842 m 14. 0 3, 322 3 10. 7 15. 8 7, 4!) 40 13. 7 15. 188 .3 7 ll. 9 6, 931 7 12. 3 7, 19B 7 33. 3 l2. 5 4, 313 so 21. 3 6, 857 .33 33. 33 16. 2 49, 375 7. 8 612 50 7. 6 850 2). 4 148 In the preceding table, the water repellency efl'ected by the compositions of this invention is exemplified by mixtures 4-13 inclusive. The inferior results obtained employing any single component of the mixture is indicated in mixtures 1 through 3. Mixtures 14, 15, and 16 show the water repellency obtained employing binary mixtures AB, BC, and AC. Unimpregnated leather samples have first drop" values ranging from so to so. I

EXAMPLE 2 y In the same manner as in Example 1, leather samples were impregnated employing a 15 per The benefits of this invention are carbon radicals attached thereto.

some

cent solids solution of mixtures composed of equal weight portions of compositions A, B, and the titanium compounds listed in Table II.

Table II Average Average No. oi Compound percent flexes pickup first drop tetra 2-ethyl hexyl titanatc l2. 2 26, 000 octylcne glycolyl titanate 14. B 5, 133 tetra isopropyl titanate l3. 5 9, 647

The above titanium compounds are commercially available fluids soluble in Stoddard Solvent or naphtha mineral spirits. They were prepared by reacting a mol of tetramethyl or tetraethyl titanate with 4 mols oi 2-ethyl hexanol, 2-ethyl hexanediol 1,3, and isopropanol respectively.

EXANIPLE3 When leather is impregnated in the manner of Example 1. with a composition consisting of equal parts by weight of compositions A and B of Example 1 and tetramethyl titanate or tetradodecyl titanate, excellent water repellency is obtained.

EXAMPLE 4 Mixtures comprisingequal parts by weight of compositions A and C and 100 cs. phenylmethylsiloxane or ethylvinylsiloxane fluids, bring about excellent resistance to water penetration when impregnated into leather in accordance with Example 1.

EXALEPLES when a titanium ester such as THOCHaCHaCHaCH=CHaJ 4.

which may be prepared by ester interchange of tetramethyl titanate with beta-allyl-ethyl alcohol, is employed in place of tetrabutyl titanate in the mixtures of Example 1. equivalent results phatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy radicals; (2) 5 to 70 per cent by weight of a methyl polysiloxane copolymer composed of trimethylsiloxane units and SiO: units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to 2.5:1; and (3) 15 to 80 per cent by weight of a polysiloxane having the general formula where R is a radical selected from the group consisting of alkyl and [alkylene] allceiwl radicals of less than 4 carbon atoms, and monocyclicaryl radicals and "n" has an average value of 2 to 2.9. each silicon atom in said polysiloxane (3) having at least one of the defined hydrosilicon atom in said 7 2. The composition of claim 1 where R is an alkyl radical of less than 4 carbon atoms.

3. The composition of claim 1 wherein R is a .butyl radical.

4. As an article of manufacture, leather impregnated with 1 to 50 per cent by weight based on the weight of the leather of the composition of claim 1.

5. As a composition of matter a mixture comprising (1) 15 to 50 per cent by weight of a titanium compound selected from the group consisting of titanium compounds having the general formula Ti(OR)4 and aliphatic hydrocarbon soluble partial hydrolyzates thereof, in said compounds B being selected from the group consisting of aliphatic hydrocarbon radicals of less than 13 carbon atoms and hydroxylated aliphatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy radicals; (2) 5 to per cent by weight of a methylpolysilcxane composed of trimethylsiloxane units and SiO: units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to 2.5:1; and (3) 15 to 80 per cent by weight of a polysiloxane having the formula (CH ,SiO

where "n has an average value of 2.0 to 2.9, each silicon atom in said polysiloxane (3) having at least one methyl radical attached thereto.

6. The composition of claim 5 where R is butyl.

'7. As an article of manufacture, leather impregnated with l to 50 per cent by weight based on the weight of the leather of the composition of claim 5.

8. As a composition of matter a mixture comprising (1) 15 to 50 per cent by weight of a titanium compound selected from the group consisting of titanium compounds having the general formula THOR); and aliphatic hydrocarbon soluble partial hydrolyzates thereof, in said compounds R being selected from-the group consisting of aliphatic hydrocarbon radicals of less than 13 carbon atoms and hydroxylated aliphatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy groups; (2) 5 to '10 per cent by weight of a methylpolysiloxane copolymer composed of trimethylsiloxane units and S102 units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to [2.521;] 1.5:1; and (3) 15 to 80 per cent by weight of a polysiloxane having the formula where n" has an average value of 2.0 to 2.9, each polysiloxane (3) having at attached thereto.

claim 8 wherein R is a least one methyl radical 9. The composition of butyl radical.

10. As an article of manufacture, leather impregnated with from 1 to 50 per cent by weight based on the weight of the leather 0! the composition of claim 8.

References Cited in the die of this patent or the original patent UNITED STATES PATENTS Number Name Date 2.512.058 Gulledge June 20, 1950. 7 2,568,384 Cheronis Sept. 18. 1951 

